1. Technical Field
The present invention relates to an optical sampling apparatus. In particular, the present invention relates to an optical sampling apparatus used in measurement of an optical pulse waveform by an optical sampling oscilloscope, or the like.
2. Related Art
Measurement of an optical pulse waveform is not only necessary for evaluating quality of an optical signal at a receiving end in optical communication, but can also be used to monitor signal quality in a node of an optical network or a signal relay device. Along with increased capacity of fiber optic communication, progress is being made in commercialization of next-generation fiber optic communication systems that can transmit and receive signal light at a bit rate of 160 Gb/s or more. To realize such a high capacity communication system, an apparatus that accurately measures a pulse waveform of the optical signal with the high bit rate described above is essential.
As an apparatus that measures the optical pulse waveform having a bit rate of 160 Gb/s or more, an apparatus that measures the light pulse waveform based on intensity correlation signal light obtained by mixing the light to be measured and the sampling light and inputting the mixed light into a nonlinear medium to cause a nonlinear optical effect is known as in, for example, Japanese Patent Application Publication No. 2006-194842.
In the measurement described above, it is necessary to input as the sampling light pulse light having a shorter duration in order to measure the pulse waveform of the light to be measured with a higher time resolution. However, the intensity correlation signal obtained using the light to be measured and the sampling light having the short duration has a low signal strength, so that the S/N ratio is low, which results in difficulty in performing the measurement with a high sensitivity.